1. 录入全部歌手的基本信息：歌手编号及姓名。 2. 10 个评委的打分随机生成，分数在 0-100 之间，歌手最后得分去掉一个最高分和最低分，求平均值。 3. 显示全部歌手的信息。 4. 对全部歌手按成绩排序。 5. 根据歌手编号，查询该歌手全部信息。 6. 添加一个歌手。 7. 将全部歌手信息保存到一个文件之中。 8. 建立如图 28.1 所示菜单实现上述功能。编程

好的，以下是 C 语言的代码实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define MAX_SINGERS 100
#define MAX_NAME_LENGTH 50

// 歌手结构体
typedef struct Singer {
    int id;
    char name[MAX_NAME_LENGTH];
    int scores[10];
    float avg_score;
} Singer;

Singer singers[MAX_SINGERS];
int singer_count = 0;

// 随机生成分数
int random_score() {
    return rand() % 101;
}

// 计算平均分
void calculate_avg_score(Singer *singer) {
    int max_score = -1, min_score = 101, total_score = 0;
    for (int i = 0; i < 10; i++) {
        int score = singer->scores[i];
        if (score > max_score) {
            max_score = score;
        }
        if (score < min_score) {
            min_score = score;
        }
        total_score += score;
    }
    total_score -= max_score + min_score;
    singer->avg_score = total_score / 8.0;
}

// 录入歌手信息
void input_singer() {
    if (singer_count >= MAX_SINGERS) {
        printf("歌手数量已达到上限，无法添加新歌手！\n");
        return;
    }
    Singer *singer = &singers[singer_count];
    printf("请输入歌手编号：");
    scanf("%d", &singer->id);
    printf("请输入歌手姓名：");
    scanf("%s", singer->name);
    for (int i = 0; i < 10; i++) {
        singer->scores[i] = random_score();
    }
    calculate_avg_score(singer);
    singer_count++;
}

// 显示全部歌手信息
void show_all_singers() {
    printf("编号\t姓名\t平均分\n");
    for (int i = 0; i < singer_count; i++) {
        Singer *singer = &singers[i];
        printf("%d\t%s\t%.2f\n", singer->id, singer->name, singer->avg_score);
    }
}

// 按成绩排序
int compare_singers(const void *a, const void *b) {
    Singer *singer_a = (Singer *)a;
    Singer *singer_b = (Singer *)b;
    if (singer_a->avg_score < singer_b->avg_score) {
        return 1;
    } else if (singer_a->avg_score > singer_b->avg_score) {
        return -1;
    }
    return 0;
}

void sort_singers() {
    qsort(singers, singer_count, sizeof(Singer), compare_singers);
}

// 根据编号查询
void search_singer_by_id() {
    int id;
    printf("请输入要查询的歌手编号：");
    scanf("%d", &id);
    for (int i = 0; i < singer_count; i++) {
        Singer *singer = &singers[i];
        if (singer->id == id) {
            printf("编号：%d\n", singer->id);
            printf("姓名：%s\n", singer->name);
            printf("成绩：");
            for (int j = 0; j < 10; j++) {
                printf("%d ", singer->scores[j]);
            }
            printf("\n");
            printf("平均分：%.2f\n", singer->avg_score);
            return;
        }
    }
    printf("没有找到编号为 %d 的歌手！\n", id);
}

// 保存到文件
void save_to_file() {
    FILE *fp = fopen("singers.txt", "w");
    if (fp == NULL) {
        printf("保存文件失败！\n");
        return;
    }
    for (int i = 0; i < singer_count; i++) {
        Singer *singer = &singers[i];
        fprintf(fp, "%d %s ", singer->id, singer->name);
        for (int j = 0; j < 10; j++) {
            fprintf(fp, "%d ", singer->scores[j]);
        }
        fprintf(fp, "\n");
    }
    fclose(fp);
    printf("保存文件成功！\n");
}

// 从文件读取
void load_from_file() {
    FILE *fp = fopen("singers.txt", "r");
    if (fp == NULL) {
        printf("读取文件失败！\n");
        return;
    }
    singer_count = 0;
    while (!feof(fp)) {
        Singer *singer = &singers[singer_count];
        fscanf(fp, "%d %s", &singer->id, singer->name);
        for (int j = 0; j < 10; j++) {
            fscanf(fp, "%d", &singer->scores[j]);
        }
        calculate_avg_score(singer);
        singer_count++;
    }
    fclose(fp);
    printf("读取文件成功！\n");
}

// 菜单
void show_menu() {
    printf("***************\n");
    printf("1. 录入歌手信息\n");
    printf("2. 显示全部歌手信息\n");
    printf("3. 按成绩排序\n");
    printf("4. 根据编号查询\n");
    printf("5. 添加一个歌手\n");
    printf("6. 保存到文件\n");
    printf("7. 从文件读取\n");
    printf("0. 退出程序\n");
    printf("***************\n");
}

int main() {
    srand((unsigned int)time(NULL));
    while (1) {
        show_menu();
        int choice;
        printf("请输入要执行的操作：");
        scanf("%d", &choice);
        switch (choice) {
            case 0:
                printf("程序结束，谢谢使用！\n");
                return 0;
            case 1:
                input_singer();
                break;
            case 2:
                show_all_singers();
                break;
            case 3:
                sort_singers();
                show_all_singers();
                break;
            case 4:
                search_singer_by_id();
                break;
            case 5:
                input_singer();
                break;
            case 6:
                save_to_file();
                break;
            case 7:
                load_from_file();
                break;
            default:
                printf("无效的操作！\n");
                break;
        }
    }
    return 0;
}

注：为了方便测试，随机生成分数的代码使用了 `rand()` 函数，需要在代码开头加上 `#include <time.h>` 和 `srand((unsigned int)time(NULL));`。